Emacs: Best Undo/Redo Mode

Xah Lee, 2011-04-08, 2013-04-30

There are a few packages for redo. Of the ones i've used are:

• 〔redo.el〕 by Kyle E. Jones, 1997.
• 〔redo+.el〕 original by Kyle, updated by S Irie, 2008.
• 〔undo-tree.el〕 Toby Cubitt 2009.

The redo.el works ok, but occasionally it corrupts your undo… meaning that you know there's more undo/redo but wasn't able to get to it. This happens perhaps once a month.

The redo+.el is supposed to update/modernize the code. Unfortunately, i didn't have luck with it. These Kyle based redo modes are ≈200 lines of elisp, each.

The undo-tree.el i just installed today, and it seems the best of the bunch. It includes a redo command “undo-tree-redo”. Plus, it gives you commands to visualize the full emacs undo tree. This package is about 2k lines of code, not counting comments.

Installing undo-tree-mode

If you have emacs 24, you can install undo-tree-mode from the MELPA repository. 〔☛ A Guide on Emacs Package System〕

Or, download “undo-tree-mode” at Source www.dr-qubit.org

then, place it at 〔~/.emacs.d/undo-tree.el〕.

then, place the following in your emacs init file:

(require 'undo-tree)
(global-undo-tree-mode 1)

By default, the keys to undo are {【Ctrl+/】, 【Ctrl+_】}. The keys to redo are: {【Ctrl+?】, 【Meta+_】}

〔undo-tree-mode.el〕 is written by Toby Cubitt http://www.dr-qubit.org/emacs.php . Thanks Toby.

Setting Up Undo Redo Keys

You can set them to the Z key:

(defalias 'redo 'undo-tree-redo)
(global-set-key (kbd "C-z") 'undo) ; 【Ctrl+z】

(global-set-key (kbd "C-S-z") 'redo) ; 【Ctrl+Shift+z】;  Mac style

(global-set-key (kbd "C-y") 'redo) ; 【Ctrl+y】; Microsoft Windows style

Thanks to David Capello for suggesting undo-tree-mode.